What Is Smart Dust, Anyway?

Share

What Is Smart Dust, Anyway?

Facial-recognition cameras are so 2001 - at least when it comes to stirring up paranoia among privacy hand-wringers. The bogeyman of the moment is smart dust, a network of speck-sized machines that can suss out whether sarin is in the air, enemy troops are around the corner, or the mean temperature on Mars has dropped. Smart-dust particles are designed to float through the air as innocuously as dandelion seeds, gathering and transmitting data in real time.Pinkroom (www.pinkroom.net)

The father of smart dust is UC Berkeley electrical engineering professor Kris Pister. Six years ago, he went to Darpa with a proposal for outfitting silicon slivers with microscopic surveillance equipment. Such infinitesimal devices are commonly known as microelectromechanical systems, or MEMS. Creating the dust isn't so different from making computer chips: You start with a silicon wafer, then coat it with a metal film that allows microstructures to be etched into its surface. Ultrasound or a diamond saw is then used to shatter the wafer.

The tough part is getting those little pieces to do something useful. Pister's latest functional MEMS - each smaller than an aspirin - are still 100 times bigger than his ultimate target of 1 cubic millimeter. The motes come equipped with sensors that can detect when metal objects, like tanks, move and disrupt the Earth's magnetic field. A lone particle's magnetometer reading isn't much good to a battlefield commander. But a cloud of motes swapping information like a peer-to-peer network can provide a detailed portrait of an advancing tank battalion or an ambush attack.

Pister, who heads the Berkeley startup Dust Inc., wanted to give his motes miniature radios to communicate. But each mote required so much power, he couldn't build one smaller than 200-cubic-millimeters. Then one of his grad students had a breakthrough: a stripped-down transmitter that uses less juice but can broadcast data about 30 feet. Currently, Pister's smart dust relies on solar cells measuring just a few millimeters in diameter. But at that size, power storage could be a problem, so he's considering going nuclear. Giving each mote a long-term energy supply might eventually be as simple as sprinkling it with a radioactive isotope. Pister's MEMS also carry a light-on-the-memory operating system, called TinyOS, that was designed for the project.

Five hundred miles south of Pister's startup, a Darpa-funded team at UC San Diego is putting another spin on smart dust: antiterror intel. Michael J. Sailor, a chemistry professor, is testing a family of motes designed to sniff out deadly toxins. Sailor's particles contain chemicals that change color when in contact with nerve agents, germs, or other potential terrorist weapons. The idea is to illuminate these dust clouds from afar with a laser, which can pick up telltale color shifts.

The wee technology has all sorts of possible applications, including monitoring home energy use and aiding interplanetary exploration. But there is also a sneaking fear that smart dust could one day be misused by jealous exes, overzealous cops, and other privacy invaders. Not helping matters is Michael Crichton, whose latest novel features a villain obviously inspired by visions of a mote-filled future. At least there should be plenty of time to hash out the implications: Smart dust won't be out of beta for another decade.

Motes in Action1. A network of almost invisible smart dust specks is sprinkled on the battlefield.

2. Each mote acts as a computer, with its own CPU, the TinyOS, 3 K-bytes of RAM, and a radio transmitter, as seen in this diagram of the latest prototype.

3. Magnetometers in the smart dust detect the movement of large metal objects and broadcast the data.

4. A technician analyzes the signal, identifies enemy tanks, and calls for an attack.